[Status Bar Refactor] Make StatusBarDemoMode part of the fragment

component so it's re-created each time we get a new status bar view.

This also lets us remove some StatusBar.java #getStatusBarView calls
because the demo mode class now just gets access to the views via its
dagger component.

Bug: 209005990
Bug: 205609837
Test: manual (verified demo mode still works)

Change-Id: I4522f2d0c09260369725286a72e3e664abbb87db